08.15.11 6:33 AM ET

Glee: The 3D Concert Movie, the new film based on “Glee Live! In Concert,” the tour starring cast members of the Fox dramedy, is one of the biggest bombs of the summer, earning a paltry $5.7 million at the box office this weekend, according to studio estimates. For the sake of comparison, the biggest kids’ movie flop of the year, Mars Needs Moms, opened to $6.9 million in March.

In the film, Lea Michele’s showstopper is the Barbra Streisand medley she’s performed often, “Don’t Rain on My Parade.” On Sunday, that song seemed to double as a defense for the movie. Ryan Murphy said that even though Glee 3D barely made any money, it cost even less. A Fox TV executive put the blame on the film’s marketing team.

But after watching the movie at the theater over the weekend, the meager attendance wasn’t the most startling revelation. It was how little screen time the film devoted to the actual cast: Lea Michele, Chris Colfer, Cory Monteith, etc. Executive producer Ryan Murphy received a lot of flak this summer for his announcement—and subsequent retraction—that he was axing the show’s biggest actors after next season. Somehow, he also managed to prevent Glee's stars from starring in their own movie.

Instead, say hello to Janae Meraz, Trenton Thompson, and Josey Pickering! Never heard of them? Neither has anybody else. The trio of Gleeks acts as a modern-day Greek chorus whose stories monopolize most of Glee: The 3D Concert Movie. Rather than following the actual singers backstage, the cameras linger at these teenagers’ homes, which are full of a different kind of melodrama. Meraz is a dwarf cheerleader in high school about to attend her prom. Thompson was outed in middle school when another classmate read his journal. And Pickering, who’s a huge fan of Glee, suffers from Asperger’s. “My car was named Quinn until I crashed it,” she says. The subtext of these vignettes from director Kevin Tancharoen is that the cast of Glee is so easily irreplaceable, even unknowns can do the job. Or at least provide a sympathetic plot line to distract from the fact that the stars are nowhere to be found.

The concert movie used to be a sacred art form. Jonathan Demme’s 1984 Stop Making Sense, about the Talking Heads, didn’t have much backstage footage either, but it’s often regarded as a pinnacle in the genre, because it treated its subjects with reverence. “It’s apparent that this is a rock concert film that looks and sounds like no other,” read the New York Times review by Janet Maslin. “The sound is extraordinarily clear, thanks to the pioneering use of 24-track digital recording. And the film’s visual style is as coolly iconoclastic as the Talking Heads itself. Mr. Demme has captured both the look and the spirit of this live performance with a daring and precision that match the group’s own.”

Other legends who let their hair down include Pink Floyd (1972’s Pink Floyd Live at Pompeii), David Bowie (1973’s Ziggy Stardust and the Spiders From Mars), The Grateful Dead (1977’s The Grateful Dead Movie), and Prince (1987’s Sign O’ the Times). Michael Jackson had 2009’s This Is It, which was released after his death. The film shows Jackson, not looking as ill as many imagined, during preparations for the final concert that never was. Perhaps it should also be eulogized as the last blockbuster concert movie targeted at adults. In May, Lady Gaga’s Monster Ball tour at Madison Square Garden aired only on HBO.

The concert movie took an unexpected U-turn thanks to Miley Cyrus. Her 2008 Hannah Montana: Best of Both Worlds Concert Tour film grossed $65 million and taught Hollywood a valuable marketing lesson: Forget about rock legends. The real money to be had from concert movies is in tweens’ purses. Young girls who can't afford to scalp tickets to see their idols live are more than happy to flock to the multiplex for the next best option, especially if the journey involves 3-D glasses.

So came the Jonas Brothers: The 3D Experience Concert and Justin Bieber’s Never Say Never, which tallied an impressive $73 million in domestic receipts in February. The latter was the brainchild of Bieber’s own manager, Scooter Braun. This infomercial masked as a documentary might have smelled like bubble gum, but the groupies didn’t care. Combine enough interviews of Bieber at home, backstage, and with his BFF Jaden Smith, and there was the illusion of proximity to the 17-year-old pop star.

In theory, the Glee movie could have pulled off the same trick. The global Glee tour was such a phenomenon, it sold out for five nights at the O2 arena in London. And then there is the compelling premise of actors on hiatus from a popular TV show traveling on a tour bus, a la the Partridge Family. We don’t know much about the cast, apart from all the tabloid reports about tantrums on set. But as the concert movie starts, the cameras are so scared to go anywhere near the actors when they aren’t performing, it reinforces the idea that there’s something to hide.

When they do appear, in brief and scripted soundbites, it’s hard to tell if they are themselves or the characters from the show. For example, the Lea Michele on Twitter has more personality than the actress who is not playing Rachel Berry in the movie. Her only memorable moment on screen is when she has a Rachel-like meltdown upon hearing that Streisand has shown up to see the show. Yet we never actually see Streisand. Barbra, can you hear them?

Many other questions linger after watching the film. Is it challenging for Kevin McHale, the actor who plays Artie, to perform in a wheelchair every night? Why does Lea Michele wear flats onstage? Did Bob Mackie design Kurt's (Chris Colfer) wardrobe? Why does Puck (Mark Salling) look as spacy as Paula Abdul? And what prompted Gwyneth Paltrow to crash the tour for a performance of Cee Lo’s “Forget You”? Since she doesn’t stick around for a confessional, just consider it another unsolved mystery.

You would think Murphy, a former journalist for The Miami Herald and the Los Angeles Times, would have done a better job of giving us answers to these questions. By parceling out to us so little, his concert movie feels more like a loud karaoke bar. It leaves such a bad taste, you can’t help but wonder if this is the beginning of the end for Glee.